In the production of thermal micro-fluid ejection devices such as ink jet printheads, a cavitation layer is typically provided as an ink contact layer for a heater resistor. The cavitation layer prevents damage to the underlying dielectric and resistive layers during ink ejection. Between the cavitation layer and heater resistor there are typically one or more layers of a passivation material to reduce ink corrosion of the heater resistor. In a typical printhead, tantalum (Ta) is used as the cavitation layer. The Ta layer is deposited on a dielectric layer such as silicon carbide (SiC) or a composite layer of SiC and silicon nitride (SiN).
One disadvantage of this multilayer thin film heater construction is that the cavitation and protective layers are less heat conductive than the underlying resistive layer. Accordingly, the use of these cavitation and protective layers increase the energy requirements for the printhead. Increased energy input to the heater resistors not only increases the overall printhead temperature, but also reduces the frequency of drop ejection, thereby decreasing the printing speed of the printer.
In response to the need to reduce the energy consumption (e.g., as discussed above), the industry has investigated different materials for its protective layers. One such material is diamond-like carbon, or in some instances doped diamond-like carbon. While diamond-like carbon has a conductivity value more near that of the underlying resistive layer, and thus addresses the energy requirements, it is often difficult to integrate into current process flows (e.g., whether it be in printheads or other semiconductor devices).
Accordingly, what is needed in the art is a method for incorporating diamond-like carbon into current process flows, whether related to micro-fluid ejection devices or not, that does not experience the drawbacks of previous processes.